1. Field of the Invention
The present invention relates to an intermittent application method and apparatus, and an inkjet recording method and apparatus, and to technology for intermittently applying an application liquid with high accuracy onto a supporting body by means of an application cylinder, and more particularly, to technology for intermittently applying a treatment liquid with high accuracy onto a supporting body (for example, an intermediate transfer body) in a two-liquid transfer type of inkjet recording method and apparatus wherein an ink image formed by causing two liquids, such as ink and treatment liquid, to react together on an intermediate transfer body is transferred onto a recording medium.
2. Description of the Related Art
An inkjet recording method performs recording by ejecting droplets of ink respectively from a plurality of ejection nozzles which are formed in an inkjet head, and this type of method is used widely since it enables images of high quality to be recorded onto recording media of a wide variety of types, while incurring low running costs and producing little noise during the recording operation.
There are known inkjet recording methods in which an ink image is formed temporarily on an intermediate transfer body by ejecting droplets of ink onto the intermediate transfer body from an inkjet head, and the ink image is then transferred onto a recording medium (for example, paper) by a roller, in a transfer part. According to a transfer type of inkjet recording method of this kind, it is possible to remove ink solvent (for example, water, or the like) on the intermediate transfer body by means of a solvent removal roller or the like, and then transfer the image onto the recording medium. Therefore, problems such as bleeding of the image, printing through to the rear surface, deformation of the recording medium (so-called cockling), and the like, which are caused by the presence of ink solvent, are avoided, and therefore an image of high quality can be obtained.
The intermediate transfer body may be an endless belt formed in the shape of a band, which is conveyed by being wrapped about a plurality of rollers, or it may be a sheet-fed intermediate transfer body which is conveyed on a conveyor belt, or the intermediate transfer body may be a drum-shaped member.
Furthermore, an inkjet recording method is also known which is a two-liquid method of promoting fixing of ink by forming an ink image by causing reaction of two liquids, namely, an ink and a treatment liquid which aggregates the ink. A two-liquid method of this kind is used also in a system which forms an image directly on a recording medium, in addition to a transfer system such as that described above.
Japanese Patent Application Publication No. 2002-321350 and Japanese Patent Application Publication No. 2005-170036 disclose related art technology which applies a two-liquid method to a transfer type of inkjet recording method. These publications state that it is possible to use, as a device which applies treatment liquid to an intermediate transfer body, an application roller system or spray nozzle system which is able to apply treatment liquid to the whole surface of the intermediate transfer body, as well as ejection nozzles which eject treatment liquid as liquid droplets.
However, the full surface of the intermediate transfer body does not necessarily form an image region for forming an ink image, and there may be an image region where an ink image is formed and a non-image region where an ink image is not formed. For example, sheets of a recording medium, such as cut paper, are supplied at a uniform spacing to the transfer roller, and the portion of the intermediate transfer body corresponding to the uniform spacing forms a non-image region.
Consequently, as shown in FIG. 13A, intermittent application is required in which a treatment liquid is applied only to the image regions 12A (black diagonally hatched regions) of the intermediate transfer body 12 which correspond to the recording media, and treatment liquid is not applied to the non-image regions 12B (white regions) of the intermediate transfer body which correspond to the uniform spacing. Furthermore, even if band-shaped recording media are supplied continuously to the transfer unit, then since an image region 12A and a non-image region 12B are formed on the intermediate transfer body 12 as shown in FIG. 13B, intermittent application for applying treatment liquid only onto the image regions 12A (black diagonally hatched regions) is required. In other words, on-demand application is required for applying treatment liquid in an intermittent fashion, only to the required regions of the intermediate transfer body 12.
If treatment liquid is applied to the whole surface of the intermediate transfer body 12 as in the related art, then not only is the treatment liquid used wastefully, but this can also lead to problems such as the occurrence of foreign material and increase in the cleaning load, as described below.
In other words, since the treatment liquid which has been applied to the non-image regions 12B of the intermediate transfer body 12 may adhere to the roller of the transfer unit, and the like, during transfer, then if the treatment liquid adheres to the roller in this way a large number of times, the treatment liquid forms foreign matter, which is then transferred to the recording medium.
As a countermeasure against foreign material, a composition is possible in which a cleaning apparatus for the intermediate transfer body 12 is provided on the downstream side of the transfer unit, but if there is a large amount of treatment liquid remaining on the intermediate transfer body 12, then the cleaning load will be very great. In particular, if the treatment liquid includes components such as a strong acidic material or alkali material, then these can be causes of degradation of the intermediate transfer body 12 itself, or of corrosion of the roller of the transfer unit.
Furthermore, the length of the non-image region 122B where treatment liquid is not applied to the intermediate transfer body 12 is generally an extremely short length of the order of a millisecond (msec) when converted to time. Consequently, highly accurate application technology is required in order to halt the application instantaneously for the non-image region 12B of the intermediate transfer body 12. Moreover, due to demands for image quality of high resolution and reduced drying time for transfer, technology is also required which is able to apply the treatment liquid in an extremely thin film of several microns, at a uniform thickness, on the intermediate transfer body 12.
If the application roller system and the spray nozzle system described in Japanese Patent Application Publication No. 2002-321350 and Japanese Patent Application Publication No. 2005-170036 are considered in view of these requirements relating to the application of treatment liquid, then although a spray nozzle can turn the spray of treatment liquid on and off with relatively good accuracy, by controlling the opening and closing of a valve, for example, it is difficult to apply an extremely thin film uniformly.
On the other hand, an application apparatus which comprises an application cylinder, such as an application roller apparatus, is excellent for applying a uniform thin film, but this structure is not beneficial for switching the supply of treatment liquid on and off. Therefore, such an apparatus is not suitable for highly accurate intermittent application in which the application of liquid is halted instantaneously when changing from the image region 12A to the non-image region 12B on the intermediate transfer body 12.
In view of these circumstances, an apparatus which is capable of highly accurate intermittent coating by comprising a function for instantaneously halting application and restarting application is required as an application apparatus comprising an application cylinder, and an intermittent application apparatus of this kind would be highly valuable not only in the field of applying treatment liquid in an inkjet recording apparatus, but also in various other technical fields.